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| Credit:biologie.uni-hamburg.de |
Hormone is a chemical substance, secreted by endocrine gland, carried by the blood, which alters the activity of one
or more specific target
organs and is then destroyed by the liver.
1. Chemical control of metabolic activity by adrenaline
Adrenaline is a hormone
secreted by adrenal glands. When
you are frightened, excited, your brain sends impulses along a verve to your
adrenal glands. This makes them secrete adrenaline into the blood.
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| Adrenal gland is situated above each kidney. |
Adrenaline helps you to cope
with danger:
1. ↑ heart
rate → supply O2 to
brain and muscle more quickly →↑ energy for action (fighting, running…).
Contract blood
vessels in skin and digestive system → they carry very little blood → supplies
blood back to vital organs (brain and muscles).
2. Stimulate liver to convert glycogen to glucose, ↑ glucose release into the blood by liver → extra glucose for muscle →help muscle to
contract.
Examples of situations in which adrenaline secretion increases
Adrenaline is needed and
secreted in a “fright, fight or flight” situation.
E.g.: When you are facing danger, for example, a
masked man with a gun is approaching you.
- Your brain sends a signal to the adrenal glands,
to start secreting and pumping adrenaline into the bloodstream.
- the actions of the adrenaline is listed above
2. Comparison of nervous and hormonal control
systems
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ReplyDeleteAdrenaline makes the muscles and the liver convert glycogen to glucose. While glucogon only makes the liver convert glycogen to glucose.
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ReplyDelete